The receptive fields will be mapped of neurons in the striate cortex (area 17), the peristriate belt (area 18) and in the temporal cortex of treeshrews (Tupaia glis). The behavior of such neurons in intact cortex will be compared with those found at varying times following ablations of parts of the visual cortex. The residual visual discriminating ability of operated animals will be tested in the behavior laboratory prior to electrophysiological experiments. Two principal questions are asked. First, what types of neural responses are required to make what types of visual discriminations; and second, does the behavior of neurons remaining after partial cortical ablations differ from the behavior of neurons found in the same cortical area in intact brain. This proposal concerns electrophysiological experiments only, behavioral testing will be conducted in Dr. Diamond's laboratory and funded independently from this grant.